A number of approaches have been investigated to impart fire resistance to polyester fibers with varying degrees of success. In general, it has been extremely challenging to impart fire resistance into polyester fibers without detracting from other important properties such as processability (i.e., melt viscosity increase), ability to melt spin fibers, and mechanical properties. Thus, there is a recognized need to provide fire resistance to polyester fibers without detracting from melt processability, strength, modulus, dyeing and heat-setting characteristics as compared to the unmodified polyester.